Field of the Invention
The present invention relates to an image forming apparatus for forming an image on a recording material.
Description of the Related Art
In an image forming apparatuses, such as a multifunction peripheral, a printer and the like using an electrophotographic method, there is a problem in that scratches occur on an image surface of a sheet when the sheet rubs against a conveyance guide after passing through a fixing unit. Particularly in recent years, in the course of an increased demand for improvement in printing speed and miniaturization of image forming apparatus, a sheet conveyance speed becomes faster and it becomes necessary to reduce a curvature of a sheet conveyance path to design a space-saving product. In addition, there is an increased demand for improvement in quality of a printing outcome. Because of the above-described situation, scratches occurring on the image surface caused by the sheet rubbing against the conveyance guide have been increasingly treated as a major issue.
Japanese Patent Application Laid-Open No. 2000-109275 discusses a configuration in which a speed of a roller on a downstream in a conveyance direction is set to be faster than that of a roller on an upstream in a conveyance direction when a sheet is conveyed through a curved conveyance path while an image surface thereof is facing toward an outer guide. With this configuration, it is possible to prevent scratches occurring on the image surface of the sheet caused by the image surface of the sheet contacting the outer guide.
There is provided an image forming apparatus including an inversion mechanism employing a switchback system, capable of selecting between a face-down discharge in which a sheet is discharged with a surface on which an image is formed facing downward and a face-up discharge in which a sheet is discharged with a surface on which an image is formed facing upward. In the above image forming apparatus, orientation of a surface on which an image is formed is inversed when the sheet is discharged using the face-up discharge or the face-down discharge. Accordingly, in a case where a speed setting is fixed as in the configuration described in Japanese Patent Application Laid-Open No. 2000-109275, there is a risk in which an image surface may rub against a guide and scratches on the image surface may occur.